C-RAN (Cloud-RAN (Radio Access Network)), sometimes referred to as Centralized-RAN, is a proposed architecture for cellular networks. C-RAN is a centralized, cloud computing-based architecture for radio access networks that supports 2G, 3G, 4G and future wireless communication standards. Its name comes from the four ‘C’s in the main characteristics of C-RAN system, “Clean, Centralized processing, Collaborative radio, and a real-time Cloud Radio Access Network”.
Compared to a traditional cellular network, a C-RAN has a system structure, where distributed RF (radio frequency) units called remote radio head (RRH) receive the signals and communicates the signals to a centralized baseband unit (BBU) via front-haul. The front-haul is bandwidth limited.
It is desirable to have methods apparatuses, and systems for precoding multi-carrier signal at multiple locations (layers).